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Transcript of the Advisory Committee on Reactor Safeguards e-Vinci Subcommittee Meeting, August 21, 2024, Pages 1-103 (Open)
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Official Transcript of Proceedings NUCLEAR REGULATORY COMMISSION

Title:

Advisory Committee on Reactor Safeguards eVINCI Subcommittee Docket Number:

N/A Location:

teleconference Date:

08-21-24 Work Order No.:

NRC-0016 Pages 1-50 NEAL R. GROSS AND CO., INC.

Court Reporters and Transcribers 1716 14th Street, N.W.

Washington, D.C. 20009 (202) 234-4433

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(202) 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgross.com 1

1 2

3 DISCLAIMER 4

5 6

UNITED STATES NUCLEAR REGULATORY COMMISSIONS 7

ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 8

9 10 The contents of this transcript of the 11 proceeding of the United States Nuclear Regulatory 12 Commission Advisory Committee on Reactor Safeguards, 13 as reported herein, is a record of the discussions 14 recorded at the meeting.

15 16 This transcript has not been reviewed, 17 corrected, and edited, and it may contain 18 inaccuracies.

19 20 21 22 23

1 UNITED STATES OF AMERICA 1

NUCLEAR REGULATORY COMMISSION 2

+ + + + +

3 ADVISORY COMMITTEE ON REACTOR SAFEGUARDS 4

(ACRS) 5

+ + + + +

6 eVINCI SUBCOMMITTEE 7

+ + + + +

8 WEDNESDAY 9

AUGUST 21, 2024 10

+ + + + +

11 The Subcommittee met via Teleconference, 12 at 1:00 p.m. EDT, Thomas E. Roberts, Chair, presiding.

13 14 COMMITTEE MEMBERS:

15 THOMAS E. ROBERTS, Chair 16 RONALD G. BALLINGER, Member 17 VICKI M. BIER, Member 18 VESNA B. DIMITRIJEVIC, Member 19 CRAIG A. HARRINGTON, Member 20 GREGORY H. HALNON, Member 21 WALTER L. KIRCHNER, Member 22 ROBERT P. MARTIN, Member 23 SCOTT P. PALMTAG, Member 24 MATTHEW W. SUNSERI, Member 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

2 ACRS CONSULTANTS:

1 DENNIS BLEY 2

STEPHEN SCHULTZ 3

4 5

DESIGNATED FEDERAL OFFICIAL:

6 WEIDONG WANG 7

8 9

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

3 CONTENTS 1

2 Call to Order, Opening Remarks and Objectives..

4 3

Tom Roberts, ACRS Subcommittee Chair 4

Staff Opening Remarks..............

9 5

Stephen Philpott, NRR 6

Reactor Design Overview Summary......... 11 7

Anthony Schoedel, WEC........... 11 8

Meredith Heh, WEC............. 12 9

Principal Design Criteria Topical Report

.... 25 10 Patrick Boyle, NRR

............ 25 11 Greg Oberson, NRR............. 27 12 Opportunity for Public Comment (None)...... 49 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

4 P R O C E E D I N G S 1

(1:00 p.m.)

2 CHAIR ROBERTS: It is now 1:00 o'clock and 3

this meeting is called to order.

4 This is a

meeting of the eVinci 5

Subcommittee of the Advisory Committee on Reactor 6

Safeguards.

7 I am Tom Roberts, Chair of today's 8

Subcommittee meeting.

9 ACRS members in attendance in person are 10 myself, Vicki Bier, Bob Martin, Ron Ballinger, and 11 Craig Harrington. Online, we have Greg Halnon, I can 12 see, and everybody else is off the screen.

13 So, if you could just identify the 14 members, or the members can identify themselves.

15 That's probably the way to do this.

17 Matt.

18 CHAIR ROBERTS: Matt Sunseri?

19 MEMBER SUNSERI: Yes.

23 CHAIR ROBERTS: Okay. Thank you, guys.

25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

5 CHAIR ROBERTS: Okay.

1 And our consultants in the room are Steve 2

Schultz and Dennis. I see Dennis is online, Dennis 3

Bley.

4 So, if there is anybody who is either a 5

member or a consultant that I didn't introduce, please 6

speak up now.

7 (No response.)

8 Okay. Great.

9 Mr. Weidong Wang of the ACRS staff is the 10 Designated Federal Officer for today's meeting.

11 And no member conflicts of interest were 12 identified for today's meeting.

13 During today's meeting, the Subcommittee 14 will be doing a briefing on the Topical Report and the 15 staff's Draft Safety Evaluation for the Westinghouse 16 Principal Design Criteria, or PDC, Topical Report for 17 the eVinci Microreactor.

18 The PDCs are integral to the review of the 19 unique aspects of a nuclear power plant design. PDCs 20 aid in the NRC staff's evaluation of applicable 21 regulations that allow the NRC staff to assess with 22 reasonable assurance that advanced reactor technology 23 will be conform to the proposed design bases with 24 adequate margins of safety.

25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

6 We're reviewing this report today because 1

it serves as a foundation for the safety design 2

approach of the eVinci Microreactor. And I'll add 3

that this is the first, as far as I could tell, of the 4

microreactor or small reactor advanced reactor 5

designs. It's not a gas reactor or a sodium fast 6

reactor. So, it probably will be mentioned in this 7

hearing how you adapt it to what's written for those 8

different reactor technologies to what is really a 9

very different reactor technology.

10 And so, we're going to hear presentations 11 by the NRC staff and Westinghouse regarding this 12 matter.

13 A portion of the presentations by the 14 Applicant and the NRC staff may be closed to discuss 15 information that is proprietary to the Licensee and 16 contractors, pursuant to 5 U.S. Code 552b(c)(4).

17 Attendance at the meeting that deals with 18 such information will limited to the NRC staff and its 19 consultants, Westinghouse, and those individuals and 20 organizations who have entered into an appropriate 21 confidentiality agreement with them. Consequently, we 22 will then confirm that we have only eligible observers 23 and participants in the closed portion of the meeting.

24 So, per the schedule, we actually go into 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

7 closed session in about an hour. So, at that point, 1

we'll take about a 15-minute break and the staff will 2

switch over the presentation to the closed 3

presentation and recognize folks, and we'll validate 4

everybody who is in is authorized to be in.

5 Okay. The ACRS was established by statute 6

and is governed by the Federal Advisory Committee Act, 7

FACA. The NRC implements FACA in accordance with 8

regulations found in Title 10 of the Code of Federal 9

Regulations, Part 7.

10 Per these regulations and the Committee's 11 Bylaws, the ACRS speaks only through its published 12 Letter Reports. We hold subcommittee meetings to 13 gather information for preparatory work as a part of 14 deliberations and final decisions on whether to issue 15 a Letter Report at a full Committee meeting. All 16 member comments should be regarded as the individual 17 opinion of that member only, not a Committee position.

18 The rules of participation in all ACRS 19 meetings, including today's, were announced in a June 20 13th, 2019, Federal Register Notice.

21 The ACRS section of the U.S. NRC public 22 website provides our Charter, Bylaws, member guidance, 23 subcommittee structure, agenda, Letter Reports, and 24 full transcripts of all full and subcommittee 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

8 meetings, including the slides presented.

1 The meeting notice and agenda for this 2

meeting were published there and can easily be found 3

by typing "about us ACRS" in the search field of the 4

upper right corner of the website.

5 The ACRS, consistent with the agency's 6

value of public transparency in regulation of nuclear 7

facilities, provides opportunity for public input and 8

comment during these proceedings. We receive written 9

statements and requests to make an oral statement from 10 the public, and we have set aside time on the agenda 11 at the end of the meeting -- and that will be at the 12 end if the public part of the meeting -- for any 13 comments from members and the public listening into 14 this meeting. The Subcommittee will consider all 15 public comments, as appropriate.

16 A transcript of the meeting is being kept 17 and will be made available.

18 Today's meeting is being held in-person 19 and over Microsoft Teams for the ACRS staff, the 20 members, the NRC staff, Applicant, and members of the 21 public. The Teams link information with the telephone 22 bridge was placed on the agenda on the ACRS's public 23 website.

24 When addressing the Subcommittee, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

9 participants should first identify themselves, and 1

then, speak with sufficient clarity and volume, so 2

that they can readily be heard. When not speaking, we 3

request that participants mute your computer 4

microphone on Teams or the phone, if you're on the 5

bridge line, by pressing *6.

6 Please do not use any virtual meeting chat 7

features to conduct sidebar discussions related to the 8

presentations. Rather, limit use of the meeting chat 9

function to report IT problems, such as an inability 10 to hear speakers or see presentations.

11 Also, for everyone in the room, please put 12 all your electronic devices in silent mode, including 13 muting your speakers and microphone on your laptops.

14 In

addition, please keep sidebar 15 discussions in the room to a minimum since the 16 microphones in the ceiling are live.

17

Finally, for the presenters, the 18 microphones at your tables are unidirectional. So, 19 you'll have to speak into the front of the microphone 20 in order to be heard online.

21 We're now proceeding with the meeting.

22 Does someone from the staff management want to start 23 off the meeting?

24 MR. PHILPOTT: Thank you. Yes.

25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

10 Good afternoon. My name is Steve 1

Philpott. I'm the Acting Chief of one of the Advanced 2

Reactor Licensing Branches in the Office of Nuclear 3

Reactor Regulation.

4 As Member Roberts mentioned, the purpose 5

of this Subcommittee meeting is to discuss 6

Westinghouse's Principal Design Criteria, or PDC, 7

Topical Report for the eVinci design. The PDC Topical 8

Report describes Westinghouse's development of the 9

Principal Design Criteria for the eVinci Microreactor.

10 Westinghouse developed these PDCs using the guidance 11 from Reg Guide 1.232, "Guidance for Developing 12 Principal Design Criteria for Non-Light Water 13 Reactors," which we often refer to as the Advanced 14 Reactor Design Criteria.

15 Westinghouse is implementing the Licensing 16 Modernization Project, or LMP, methodology in their 17 licensing approach and they use the LMP process and 18 the technology-inclusive content of the application 19 project guidance to risk-inform their PDCs.

20 Westinghouse has indicated that they 21 intend to apply this PDC Topical Report in support of 22 future Standard Design Certification applications and 23 potentially other licensing applications for the 24 eVinci Microreactor.

25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

11 We would like to express our thanks to the 1

ACRS, the Subcommittee, for taking the time and your 2

interest in reviewing this important topic.

3 I also want to thank the staff, NRC staff 4

and Westinghouse, for your time preparing for this 5

meeting and the presentations that the ACRS is going 6

to hear today.

7 I did want to add one additional note.

8 Our primary reviewer from the NRC staff is not feeling 9

well today. So, when we get to the NRC presentations, 10 we may need to adjust somewhat or we'll take it as it 11 comes.

12

Yes, so we look forward to the 13 conversation today. And if there are no other 14 questions, I'll turn it over to Westinghouse.

15 CHAIR ROBERTS: This would be a good 16 demonstration of defense-in-depth of the staff.

17 (Laughter.)

18 Can we turn it over to Westinghouse?

19 MR. SCHOEDEL: Yes, thank you, Member 20 Roberts.

21 My name is Anthony Schoedel, the Advanced 22 Reactor Licensing Manager at Westinghouse, supporting 23 eVinci Microreactor design licensing.

24 Thank you all for the time here today, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

12 yourself, Member Roberts, and the other Subcommittee 1

Members.

2 And thank you to the NRC participants for 3

the technical review today and support, and getting 4

ready for all these conversations.

5 You see a few of my colleagues here with 6

me. I'll let them introduce themselves as they share 7

the speaking presentation responsibilities throughout 8

the course of the dialog today.

9 First, you're going to hear from Meredith 10 Heh, at the end of the table. She's going to lead the 11 presentation/discussion for this open portion. I'll 12 be presenting the slides here on Teams.

13 And, Meredith, without any further ado, 14 once I get them up, I think the floor is yours.

15 MS. HEH: Thank you, Anthony.

16 As Anthony said, my name is Meredith Heh.

17 I'm Advanced Reactors Licensing Engineer for the 18 eVinci Microreactor project, and I'll be your lead 19 going through the open session today.

20 Great. So today, I will begin with a 21 design overview, and then, I will go through our 22 deployment model overview. Then, I will speak on our 23 NRC pre-application engagement to date, and then, 24 follow with an overview of the PDC Topical Report.

25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

13 And then, we can go to any questions that people may 1

have.

2 So here on this slide, you can see a good 3

overview of our eVinci Microreactor design. This 4

introduces safety through passive heat pipe 5

technology, and this enables a very low pressure 6

reactor.

7 So, you can see some of our key 8

components: the shutdown rods and control drums, 9

which provide diverse means for shutdown in the 10 reactor; the graphite core block, which is our 11 moderator. And the power of the reactor is a 15-12 megawatt thermal with a fuel cycle of eight years, and 13 that fuel we'd be using is TRISO.

14 Our primary coolant is our heat pipes, 15 which is our new technology that you will hear more 16 about later today, as well as we will be using an 17 open-air Brayton cycle for power conversion. And you 18 can see the primary heat exchanger as another key 19 component in the diagram there.

20 Here on this slide, you can see an eVinci 21 Microreactor site layout. One key component we want 22 to address is that all buildings and systems are 23 aboveground. This means not a lot of excavation is 24 needed for our design.

25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

14 In the design, you can see our two-1 reactor-bay system with the power conversion module in 2

the center of the two bays. And I will describe how 3

this system works on the next slide.

4 Out-front, you can also see three 5

containers. These will be for our I&C modules and our 6

battery module.

7 And another aspect I wanted to highlight 8

is our equipment is relatively small with less than 9

three quarters overall and the building footprint 10 being just a half an acre.

11 So, after, firstly, getting our test 12 reactor demonstrated for safety future performance, 13 this will help our licensing approval, and then, we 14 can deploy our reactor, as you can see on this screen.

15 We will start by assembling in a factory, 16 and then, we can transport disassembled to the site.

17 We will install and operate at the site, and this is 18 where the two reactor bays come in. You can install 19 and operate, and then, as that reactor is operating, 20 it will operate for eight years. And when that one is 21 no longer able to be operated, you can bring in the 22 second reactor, place it into the second reactor bay, 23 and allow for a plug-and-play situation, where you 24 remove one, and then, upload and start the next.

25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

15 Then, you can allow for that other first 1

reactor to cool down, and then, once it is cooled, 2

transport it away from the site. You can refuel and 3

refurbish that reactor, or if it has reached its end 4

of life, send it to decommissioning and the fuel to a 5

fuel storage facility.

6 This pre-application will be --

7 CHAIR ROBERTS: Meredith, I just have two 8

quick questions on radiation levels. It's not clear 9

from the figure in that slide how much shielding there 10 is in that blue building to keep the personnel safe in 11 this reactor.

12 It's also not clear on the next slide, 13 transport away from site, what kind of delays you need 14 before you can transport safely on the road.

15 Can you give us a little perspective on 16 that, on both of them?

17 MR. SMITH: This is Matt Smith from 18 Westinghouse.

19 So, in terms of shielding, there's 20 actually two structures shown there. There is a 21 concrete structure that provides the majority of the 22 shielding there, yes.

23 MS.

SPALDING:

I can talk about 24 transportation.

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16 MR. SMITH: Yes. Yes, I'll turn it over 1

to Amanda.

2 MS. SPALDING: Hi. This is Amanda 3

Spalding, also a part of the eVinci Microreactor 4

licensing team.

5 So, the question on transportation, we 6

will be certifying a reactor transportation cask for 7

the reactor module, both to ship onsite with the fresh 8

fuel and ship away with the spent fuel. And we will 9

make sure that it meets the Part 71 regulations for 10 fissile packages.

11 So, that cool-down period, while we're 12 still developing what that would actually look like, 13 it will be to ensure that we do meet the Part 71 14 regulations to ship it offsite.

15 CHAIR ROBERTS: Okay. Thank you.

16 MS. HEH: Thank you, Matt and Amanda.

17 There is some pre-application engagement 18 to date. Westinghouse has submitted 31 white papers 19 on various topics, including the second white paper 20 submitted being on the Principal Design Criteria 21 topic. And we have used this white paper to allow for 22 feedback and implementation into our Topical Report.

23 Speaking of Topical Reports, shown here 24 are the Topical Reports planned for submittal to the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

17 NRC, with a third -- six being submittal and a third 1

being the Principal Design Criteria Topical Report, 2

which was submitted in June of 2023.

3 So now, I'm going to go over our Topical 4

Report overview and going through the sections.

5 So, as I stated, the white paper feedback 6

on the PDC (audio interference) white paper was 7

heavily considered in our Topical Report development.

8 Section 1 of the Topical Report, the 9

purpose, states that it will cover the eVinci 10 Microreactor PDC and the basis for their selection.

11 This PDC includes safety-related and non-safety-12 related with special treatment design criteria.

13 The derivation of the eVinci Microreactor 14 PDC were based on the following applicable regulations 15 and regulatory guidance:

16 The guidance for this design criteria 17 provided in Reg Guide 1.232.

18 The GDC and Title 10 of the CFR Part 50, 19 Appendix A.

20 And also, we incorporated the safety case 21 for the eVinci Microreactor developed based on 22 NEI 18-04 and NEI 21-07 guidance, which are endorsed 23 by the NRC in Reg Guide 1.233 and 1.253.

24 And then, at the end of this Section 1, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

18 Westinghouse requested NRC review and approval of the 1

set of PDCs for the eVinci Microreactor. This 2

included the list and justification for the GDC 3

identified as not applicable to the eVinci 4

Microreactor.

5 Okay. And then, Section 2 of the report, 6

there is a summary of the eVinci Microreactor design 7

and facility description, which is, basically, the 8

summary provided on slides 3 and 4 today.

9 Section 3 of the report, a PDC development 10 summary. The PDCs were derived based on the Design 11 Criteria Reg Guide 1.232 and GDC and 10 CFR Part 50, 12 Appendix A.

13 Each GDC and DC contained in Reg Guide 14 1.232 were reviewed for applicability to our design, 15 and they were either kept as is; they were edited, or 16 they were determined to not be applicable in entirety.

17 One additional PDC was developed not based 18 GDC or Reg Guide 1.232.

19 And the eVinci Microreactor PDCs are 20 function-based. They are not structure-, system-, or 21 component-specific.

Therefore, there's no 22 differentiation or report between PDC required 23 function design criteria and PDC complementary design 24 criteria, which is described in NEI 21-07. And in a 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

19 few slides, you'll be able to see the crosswalk of how 1

we either kept the PDC as is, edited, or determined to 2

not be applicable.

3 And continuing in Section 3, we discuss 4

how NEI 18-04 and NEI 21-07 were used to risk-inform 5

the PDCs and confirm the PDCs for the eVinci 6

Microreactor safety functions and confirm that they 7

were appropriately included.

8 Examples of the ways PDCs have been 9

improvised from NEI 18-04 and NEI 21-07. Some 10 examples here were:

11 We used quality assurance PDC tests from 12 NEI 21-07.

13 We allowed for the defense-in-depth 14 process to drive the need for multiple barriers.

15 "Important to safety" text was revised to 16 "safety-significant."

17 And "postulated accident" text was revised 18 to "licensing basis events" or "design-basis 19 accidents," as applicable.

20 Table 3.3-1 in the Topical Report is shown 21 here, which is our PDC crosswalk. You can see the 22 list of applicable GDCs and whether they were pulled 23 from which appendices in Reg Guide 1.232, and whether 24 they were modified, identical, or not applicable to 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

20 the eVinci design.

1 This brings us to Section 4 of the report, 2

which is the eVinci Microreactor PDC list. As stated 3

right before the tables, each table consists of a 4

title, which is the number and title of PDC, and which 5

of those cases comes from the 10 CFR Part 50, Appendix 6

A, or Reg Guide 1.232. And the event you can see is 7

provided, the actual wording of the text.

8 Then, our position, which provides the 9

determination of whether a given ARDC, SFRDC, or 10 MHTGR-DC from Reg Guide 1.232 is adopted with or 11 without changes.

12 Modifications to the text are made in red 13 with strikeout or blue with underline for added text.

14 And then, a basis is provided which 15 provides justification and rationale for why certain 16 design criteria were determined to be applicable, and 17 also, justifies and describes changes to the text.

18 And finally, the source is provided.

19 So, we have a few examples. The first is 20 an example of one PDC that was modified from the ARDC 21 language with changes consistent to what is in 22 NEI 21-07. And this is our first PDC quality 23 standard.

24 Our second example is our one and only 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

21 newly-developed PDC for monitoring and testing. And 1

this combined multiple PDCs into a single PDC for 2

these functions.

3 Another example here is an example PDC 4

which is identical to Reg Guide 1.232. This is PDC 14 5

for reactor helium pressure boundary.

6 And finally, an example of the PDC which 7

is not applicable. The objective of PDC 27, combined 8

reactivity control system capability, as satisfied by 9

PDC 26 for reactivity control.

10 CHAIR ROBERTS: I guess I have two 11 questions, and if you want to defer them to the closed 12 session, let me know. We can do that.

13 But it's a little surprising, given that 14 this is a heat pipe reactor, which is not what was 15 really considered when either Appendix B or C of the 16 Reg Guide were written. I guess Appendix A was 17 intended to be generic.

18 You have a lot of you picked from this 19 Appendix and picked from that Appendix. But Design 20 Criteria 6, which is really a combination of a bunch 21 of others; it's not really unique to the heat pipe 22 reactor. There's nothing in here that seems to be 23 unique to a heat pipe reactor.

24 And part of the Reg Guide requirements are 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

22 to address unique features of your design and 1

determine whether or not there are design criteria 2

that are warranted based on that design.

3 So, I was wondering your perspective on, 4

you know, why is it that all of the criteria that 5

apply to a heat pipe reactor are radically covered by 6

a document that really wasn't written for a heat pipe 7

reactor?

8 MS. SPALDING: Yes. So, this is Amanda 9

Spalding again.

10 And I think we'll go into this a little 11 bit more in the closed session. But what I can share 12

here, as Meredith mentioned earlier in her 13 presentation, we developed our PDC to be based on 14 function and not specific SSCs. And so, as we went 15 through the criteria in Reg Guide 1.232 and the GDC, 16 we didn't identify any additional functions or safety 17 functions for our reactor that were not already 18 covered. And while there may be different components 19 or different systems that will perform those 20 functions, there were no additional functions.

21 So, I think that's maybe where the 22 difference is. You know, we did look at our design, 23 but we really looked at it as, what are the safety 24 functions being performed and are those covered by the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

23 intent of the design criteria?

1 We can discuss that more in the closed 2

session, but I think, for this portion, that's what we 3

would like to say now.

4 CHAIR ROBERTS: Okay. Thanks. That 5

sounds good 6

MS. SPALDING: Yes.

7 CHAIR ROBERTS: There probably will be 8

more questions in the closed session.

9 And then, the second question I had -- and 10 again, if you want to comment in your closed session, 11 that's fine -- but there were several design criteria 12 that have specific requirements for redundancy, 13 defense-in-depth, diversity, those types of things.

14 And you pretty universally change those to follow the 15 LMP core process. That will tell you whether or not 16 you need such diversity.

17 I was wondering just in general, are you 18 convinced that the LMP really covers all that or is 19 there some qualitative aspect of the LMP you're 20 counting on to identify things that may not be fully 21 modeled by the PRA?

22 MS. SPALDING: Yes, that's another great 23 question. And I think, again, we'll cover it a little 24 bit more in the closed portion; specifically, when 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

24 Matt covers some discussion design overview.

1 But our goal was to not have prescriptive 2

requirements through the PDC and allow the LMP process 3

to drive what's really necessary. So, I think, to 4

answer your question, no, we don't necessarily 5

anticipate that there are things that the PRA won't 6

identify, where the LMP process will not identify true 7

defense-in-depth adequacy, where we would need 8

redundancy or diversity. So, we're allowing that 9

process to drive the specific SSCs that will perform 10 the functions.

11 But again, we can discuss that more in the 12 closed session.

13 CHAIR ROBERTS: Okay. Good. Thanks.

14 Any other questions from members or 15 consultants before we go to the staff open session?

16 (No response.)

17 Okay. Hearing none, let's go ahead and 18 change out to the staff. You can go to the 19 presentation.

20 Your choice, you can stay back there or 21 move up to the table.

22 If you like, you can sit in the audience 23 until we start the closed session.

24 MS. SPALDING: We won't be in the hot seat 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

25 anymore.

1 CHAIR ROBERTS: Are you ready? Okay, go 2

ahead.

3 MR. BOYLE: Okay. Great. Thank you.

4 Good afternoon. I'm Patrick Boyle, 5

Licensing Project Manager at the NRC assigned to the 6

Westinghouse Electric Company eVinci project. I'm the 7

lead Project Manager for the review that Westinghouse 8

has for the Design Criteria Topical Report.

9 So today, we had Dan Beacon scheduled. He 10 is, unfortunately, unable to join us. So, Greg 11 Oberson is his Branch Chief and will be taking us 12 through the technical details of the discussion.

13 We did review our slides and determine 14 that we may require additional time in the open 15 session because in this area we can cover, and then, 16 we will be able to save that time in the closed 17 session.

18 This slide describes the agenda for the 19 NRC staff's presentation today:

20 Review the chronology of the staff's 21 review.

22 The purpose of the staff's review.

23 The staff's strategy on the Topical 24 Report.

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26 We will provide an overview of the 1

contents of the Safety Evaluation Report.

2 And then, summarize the NRC staff's 3

conclusion regarding the Westinghouse PDC Topical 4

Report.

5 Regarding the timeline of the review, 6

Westinghouse submitted Revision 0 of the Topical 7

Report in June 2023.

8 Staff accepted the Topical Report review 9

and began the staff's review in August of 2023.

10 The staff conducted clarification meetings 11 from September to October 2023.

12 Following the clarification meetings, the 13 staff issued requests for additional information in 14 November of 2023.

15 Westinghouse responded to those questions 16 in December.

17 And then, in May, Westinghouse submitted 18 Revision 1 to the PDC incorporating the RAI responses, 19 as well as the information from the clarification 20 meetings.

21 The Draft Safety Evaluation for the PDC 22 will be issued in July of 2025.

23 And now, I'd like to turn this over to 24 Greg Oberson for the technical details of the PDC 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

27 review.

1 MR. OBERSON: All right. So, as 2

mentioned, I'm Greg Oberson. I'm the Branch Chief of 3

Advanced Reactor Technical Branch 1, the Division of 4

Advanced Reactors, Nonpower Production and Utilization 5

Facilities.

6 So, I just want to, I guess, start by 7

acknowledging or sort of exercising what was aptly 8

mentioned, our defense-in-depth. So, in this case, 9

maybe the capability of the subsequent layers diminish 10 relative to the first layer -- in this case, Dan. So, 11 I'm not going to attempt it. If you could just bear 12 with me and us to appropriately replicate, and Dan 13 would add more to the presentation. So, I'm going to 14 sort of hop scotch through it.

15 But I think the important things are we 16 want to get the record of the meeting; we want to get 17 any input that you guys have had in response to what 18 you received from Westinghouse or in your prep prior 19 to the meeting. Keep note of that. And what we can 20 address here, we will, and what we can't, we'll get 21 back, and then, work through it that way.

22 So, in light of that, some things I'll 23 just sort of skip through relatively quickly. Other 24 things which I think I can somewhat capably speak to, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

28 I will. Other things which are sort of beyond me at 1

this moment, I'm going to have to defer. So, as 2

mentioned, I just appreciate your forbearance. We'll 3

do our best to do this.

4 As is obvious, the purpose of the Topical 5

Report was already well-stated. So, I don't intend to 6

just restate what was already said. But I will speak 7

to our review strategy, which was, generally, to 8

review the conformance with the Regulatory Guide 9

1.232, which was already mentioned in the prior 10 presentation by Westinghouse.

11 And notably, evaluate deviations from or 12 changes from Reg Guide 1.232. And in recognition of 13 key eVinci design features, again, as has already been 14 mentioned, this is a difference in the reactor than 15 what was perhaps envisioned when that Regulatory Guide 16 was developed. And therefore, it is necessary and 17 appropriate to look at eVinci in the context of that 18 fact.

19 And then, sort of correlated to that, 20 consider the applicability of the Appendices and 21 guidance, the novel design features, and where they 22 are appropriate, make note of that, and where there 23 are differences or key differences, make note of that 24 as well.

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29 Go to the next slide.

1 So, this is just the Safety Evaluation 2

overview. Again, I won't belabor the point here, but 3

what we noted was that the Regulatory Guide, the 4

regulations and guidance that we referenced in making 5

the Safety Evaluation findings.

6 eVinci did provide design information in 7

the Topical Report, but that was not reviewed by the 8

staff, nor did staff make any findings on the adequacy 9

of the design itself. So, we consider that to be 10 informational in the context of not supporting the 11 more fundamental evaluation of the PDCs.

12 And then, in light of what I just 13 mentioned, we sort of did the PDCs in terms of the way 14 we wrote the SE, in terms of the ones that were, 15 essentially, in Reg Guide 1.232. That's one category.

16 Another category would be those that are 17 were influenced by NEI 18-04, terminology and 18 approach, following up on what you heard this morning.

19 There are some unique ones -- fuel 20 storage, given the design concept, and then, a few 21 odds and ends that we think warrant specific attention 22 that we'll speak to.

23 And then, we noted again, as was mentioned 24 by Westinghouse staff, where there were design 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

30 criteria that were not found to be applicable to the 1

design of those.

2 And then, we'll speak to the limitations 3

and conditions.

4 So again, I won't take a lot of time in 5

restating this. I believe the members and the 6

participants in the meeting are aware of the 7

regulations and 10 CFR Parts 50 and 52 that relate to 8

the provision of PDCs, and as well, as noted, in 9

10 CFR Part 50, Appendix A, as it concerns light water 10 reactors. And again, this having been sort of stated 11 prior, I won't stick on this slide.

12 So, you can go ahead, Patrick.

13 And I'll take the same general approach 14 for this one, as these have been previously noted. Of 15 course, we view Reg Guide 1.232 as sort of like, you 16 know, base level of beyond the regulations themselves 17 and based on what we'll reference.

18 With the PDC reviews, we are sort of 19 overlaid with that. The advanced reactor technology 20 was the risk-informed regulatory guidance that relates 21 to the limitation of the LMP methodology on the 22 technology, the application of methodology, and so 23

forth, as has been previously mentioned by 24 Westinghouse in the context of other PDC reviews that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

31 you guys have done.

1 So, eVinci did a great job of these in the 2

prior presentation. But, more particularly, once we 3

go to closed session, we will speak to the eVinci 4

design features.

5 But I did want to make note of a few 6

things here that we think are relevant to the 7

consideration when we think about the applicability of 8

the PDCs to Reg Guide 1.232 to the eVinci design 9

itself. Obviously, the very fact of having TRISO fuel 10 gives it some similarity to those designs referenced 11 in Reg Guide 1.232 that also consider TRISO fuel.

12 Skipping, I guess, to the fourth bullet, 13 the heat pipe I guess maybe could be considered a 14 different design feature than what was explicitly in 15 Reg Guide 1.232. So, that warrants noting.

16 Passive heat removal. The reactor heat 17 controls functional (audio interference) is something 18 that we'll speak to, and then, the notion that a lack 19 of electrical power that is necessary to perform the 20 required safety functions, and then, maybe the very 21 last point, the transportable design. Again, there 22 are PDCs related to that, that would have not been 23 explicitly addressed in Reg Guide 1.232. It's 24 warranted to give consideration to those in our 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

32 evaluation.

1 So, as was mentioned -- it sort of came up 2

in that prior discussion by Westinghouse already --

3 given that the eVinci heat pipe reactor design itself 4

was not one that was explicitly given consideration to 5

in Reg Guide 1.232, it becomes sort of a mix and match 6

of how you sort of translate Reg Guide 1.232 today 7

relative to the eVinci design.

8 There are some aspects I think that we 9

view as being similar, at least conceptually, to the 10 SFRDCs insofar as it's sodium; it's contained within 11 the heat pipes. There are other aspects that are 12 perhaps akin to the high temperature gas reactor 13 design. You know, we note the fuel functional 14 containment and the materials, graphite, and so forth.

15 There's some similarities there, as was already 16 mentioned. PDC 6 is sort of one that rules and 17 another batch of PDCs or generic PDCs from Reg Guide 18 1.232.

19 So, as was mentioned, we sort of did the 20 PDCs into different categories, in part, due to how 21 similar we believe they are to what was in Reg Guide 22 1.232 -- again, comparing what are the functions or 23 the features of the eVinci design and how those relate 24 to some of the assumptions that are made in the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

33 reactors of this sort that were evaluated in analysis 1

for Reg Guide 1.232.

2 Listed here on this slide are a number of 3

PDCs which we found to be, essentially, identical to 4

1.232, where the language is, essentially, well, 5

verbatim the same or perhaps a wording change, as 6

noted there, "systems" to "SSCs," that we believe does 7

not have any meaningful change to the intent of the 8

allocation of the PDCs.

9 What we confirmed for the PDCs is, again, 10 at least on a functional basis, there was a direct 11 correlation between the eVinci approach and the Reg 12 Guide 1.232 sort of generic evaluation, such that we 13 could say that the bases for determining that the PDCs 14 were adequate as they relate to the designs in the 15 1.232 continue and apply to the eVinci design itself.

16 So, a number of PDCs as well concerned the 17 changes, or perhaps supporting changes, related to the 18 implementation of the LMP terminology. And this is 19 very similar to what came up this morning in the 20 discussion with the other vendor about the application 21 of the LMP to their PDCs.

22 We do note that Reg Guide 1.233, that it 23 states the applicants -- referencing the Reg Guide --

24 are expected to use the technology of NEI 18-04, and 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

34 as such, we see changes -- for instance, from 1

"important to safety" in the Reg Guide to "safety-2 significant," for instance, in licensing basis events 3

-- so as to align with the language from NEI 18-04.

4 And consequently, again, the obligation 5

for staff would be to confirm that, notwithstanding 6

the wording changes, the intent of the PDC remains the 7

same from the evaluated wording in Reg Guide 1.232 to 8

the eVinci design. And in the cases referenced, the 9

staff determined that those still didn't apply, and as 10 such, the PDCs can be determined to be acceptable.

11 So again, and continuing on with the PDCs 12 influenced by the approach, it may be worth noting 13 that Reg Guide 1.25 really was a draft at the time 14 that the Topical Report was drafted. So, the 15 refinement of PDCs into RFDCs and CDCs was not 16 implemented in this report.

17 The NEI 18-04 approach included an 18 evaluation of defense-in-depth adequacy intended to 19 address concerns related to independent redundancy, 20 diversity, and defense-in-depth, and see the Reg Guide 21 1.232 language regarding this concepts was, therefore, 22 removed. But we note that it's only acceptable if 23 used with the LMP licensing approach.

24 And, you know, once we get to the 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

35 discussion of the licensing -- sorry -- the 1

limitations and conditions, we can speak more 2

specifically to the intent of the condition as it 3

relates to the implementation of LMP methodology.

4 Okay. So, as it relates to the design of 5

the microreactor concerning the transportability, I 6

guess, or storage or transportability of the reactor 7

itself, the microreactor, there are a few PDCs -- 61, 8

62, and 63 -- that modify the language to reflect 9

reactor fuel handling and storage demand for the 10 eVinci design. So, they replace concepts of fuel 11 storage, waste, and handling with the concept of 12 reactor storage, at least as we understand it, to 13 reflect the fueled reactor unit deployment and the 14 handling approach being sought for implementation, or 15 at least being considered in the eVinci deployment 16 model.

17 It's worth noting -- and just for the 18 record, I believe the Committee is already aware of 19 this -- staff have provided a SECY paper to the 20 Commission that concerns a number of matters related 21 to technical and regulatory dimensions of fueled 22 reactor handling and storage that remain at this 23 point, from our perspective, appropriately the 24 Commission's decisionmaking process. And therefore, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

36 we would condition the PDCs on the outcome of the 1

Commission's policymaking, and then, the demonstration 2

eventually of conformance with whatever that policy 3

happens to be.

4 So, we're sort of kicking the can here, 5

effectively, until we get further direction from the 6

Commission as far as what this is going to look like 7

for the fueled reactor, like reactor deployment.

8 So, I think this sort of gets into the few 9

PDCs where just we wanted to bring it back to the 10 Committee's attention to matters where we sort of 11 evaluated, I guess, where there are some unique 12 aspects we wanted to bring the Committee's attention 13 to. They don't fit quite into the other categories 14 that we already mentioned.

15 So, PDC 12 combines portions of Reg Guide 16 1.232, Appendix A and C, and this is the suppression 17 of power oscillations. So, this reflects a broader 18 applicability of SSCs than ARDC 12, including the 19 reactor core structures, coolant control and 20 protection system. So, it reflects the use of SARRDLs 21 consistent with DC 12 rather than SAFDLs, in part, 22 because of the similarity of fuel design and 23 radionuclide retention approach for TRISO fuel. And 24 we found that to be applicable to the design and that 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

37 the underlying intent of what was evaluated in Reg 1

Guide 1.232 is applicable to the eVinci design.

2 This one may be best left for the closed 3

discussion of PDC 17. We do the same for this one, 4

microreactor control.

5 So, PDC 64, we're monitoring radioactive 6

releases. Changes to the Reg Guide reflect the 7

functional containment approach and LMP terminology.

8 So, Revision 0 of the Reg Guide included additional 9

specificity with undefined terminology. We had a 10 public meeting, and then, there was a revision to 11 PDC 64 to more closely align with ARDC 64. And again, 12 we found that the intent and underlying safety basis 13 aligns with the Regulatory Guide.

14 PDC 71 is adapted from Reg Guide 1.232, 15 Appendix B, in this case, akin to the sodium fast 16 reactor design criteria. So, applicability is to 17 helium cover gas purity of the eVinci reactor 18 canister. So, we removed, in light of eVinci design 19 language referred to the sodium primary coolant, and 20 note that eVinci PDC 73 pertains to the detection of 21 sodium (audio interference) or reactions from sealed 22 heat pipes. So, the PDC on primary cover gas purity 23 and underlying safety basis aligns with Reg Guide 24 1.232 in the context of eVinci.

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38 PDC 73, sodium detection and reaction 1

prevention and mitigation. This is adapted, again, 2

from one of the SFR design criteria. It expands upon 3

that with the requirement to assure passive heat 4

removal system availability, and the language 5

regarding sodium-concrete interactions is removed.

6 There are multiple non-concrete barriers between the 7

sodium contained in the heat pipes and the concrete 8

structures outside the reactor canister or primary 9

heat exchanger. And as such, again, the intent of the 10 safety basis aligns with Reg Guide 1.232.

11 So, PDC 74 adopts the applicable portion 12 of Reg Guide 1.232, Appendix B, language regarding 13 steam-water energy conversion systems. These are 14 grouped because eVinci relies on an open-air Brayton 15 conversion

system, as was discussed in the 16 Westinghouse portion of the presentation. And again, 17 the underlying safety basis aligns with Reg Guide 18 1.232 and remains applicable in the context of the 19 design.

20 Let's see. PDC 78, sodium heat pipe 21 interactions. Again, this is adapted from the SFR 22 design criteria, and changes, as staff noted, reflect 23 that sodium is only contained in pipes and not as a, 24 quote-unquote, "primary coolant." The language is 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

39 adapted, again, to reflect the use of the LMP 1

methodology and the defense-in-depth adequacy 2

assessment.

3 You can go on, Patrick.

4 So, I think now we'll speak to the PDCs --

5 I'm sorry -- the PDCS from Reg Guide 1.232 and the 6

design criteria that were not applicable and our 7

reasoning for that.

8 So, there are a number of PDCs related to 9

the monitoring section that were included in Reg Guide 10 1.232. And it was already mentioned that these sort 11 of get encompassed or rolled into a higher level.

12 PDC 6 may be seen as saying they don't 13 apply, but they do apply. But they are sort of rolled 14 together into a single PDC that concerns, again, the 15 capacity and monitoring, inspection and testing. So, 16 the intent in the underlying safety basis for all PDCs 17 were sort of coalesced into PDC 6. Staff assured that 18 those are appropriately addressed.

19 So, heat transport functions. So, PDCs 20 30, 31, and 33, these are not directly applicable to 21 the heat design of the eVinci reactor. Specifically, 22 the designers refer to a reactor coolant system, but 23 the staff interpretation of Reg Guide 1.232 is that 24 the eVinci design does not include any forced 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

40 convection or primary coolant as what would have been 1

meant in that regulatory guidance.

2 But, nevertheless, we did want to ensure 3

that the fundamental safety concepts or intent that 4

are meant to be addressed by those design criteria 5

were sufficiently addressed by PDCs. So, for example, 6

the reactor coolant system, we can kind of look at the 7

reactor canister, that helium pressure boundary, and 8

like can conclude for ourselves that the intent of 9

those is addressed by other aspects of the design.

10 Let's see. Heat removal emergency 11 cooling. So, these focus on adequate heat removal 12 capability to cool the core containment and associated 13 SSCs. I'll be honest, I don't know what was meant by 14 this. So, if there are any questions on that, I'll 15 have to take that back. Apologies for that.

16 The functional containment. This has 17 already been addressed, and I think Dan had mentioned 18 that this would be appropriate to address in the 19 closed session. So, we'll pick up the conversation 20 from there.

21 So, as far as limitations and conditions 22 go, you know, there's a couple proposed here, and I 23 won't read those verbatim. You have those at hand for 24 you.

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41 So, a couple of them refer to the 1

implementation of LMP methodology, recognizing, again, 2

as we've already discussed, that these are preliminary 3

designs, and as the LMP process continues to unfold, 4

as necessary, we will ensure that the outcomes of 5

those are iterated back into for the development of 6

the PDCs; and also, that to the degree that sort of 7

language related to implementation of the PDC reflects 8

terminology from the LMP and departures from, for 9

instance, Reg Guide 1.232, that those are acceptable 10 insofar as the user of the Reg Guide -- I'm sorry --

11 the user of the Topical Report conforms with the LMP 12 process.

13 Let's see. Then, the third one relates, 14 again, to the matters of reactor fuel storage and 15 transportation --

16 CHAIR ROBERTS: Excuse me. Could you go 17 back?

18 MR. OBERSON: Sure.

19 CHAIR ROBERTS: Yes, there's two questions 20 that may be editorial, maybe not. But the second 21 sentence of the first one says, "design changes and 22 associated policy implementations." And it seems like 23 from the first sentence, it's the LMP implementation 24 of the entire design, not just the changes that are 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

42 made to the design, is that right?

1 MR. OBERSON: Yes.

2 CHAIR ROBERTS: It seems the word 3

"associated" doesn't belong there.

4 MR. OBERSON: Yes, we may have to check 5

that wording out. I think the intent of that, 6

fundamentally, is to ensure that, if the LMP had a 7

limitation, it doesn't necessitate a revision to the 8

PDCs in whatever manner. We would have assurance that 9

those would be, like I said, that those would be 10 accounted for. So, yes, we'll take a note, a project 11 to take a look at the wording and see. Thank you for 12 drawing the attention to that.

13 CHAIR ROBERTS: Yes. And the second one 14 is No. 2, why isn't PDC 16 listed there?

15 MR. OBERSON: Again, I'll have to take a 16 note of that to follow back up with you on that.

17 CHAIR ROBERTS: So, that's a functional 18 containment --

19 MR. OBERSON: Yes.

20 CHAIR ROBERTS: -- and the words were 21 taken out about how to --

22 MR. OBERSON: Yes. Dan, again, if you 23 want to join? I apologize, Dan, I'm not doing you 24 justice to what you can do here.

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43 MR. BEACON: Oh, that's no problem. I 1

snuck back into the meeting from my hotel real quick.

2 So, I think our position is that we do 3

plan to put 16 into that list.

4 MR. OBERSON: So, as you heard, it was not 5

included. That was an oversight or change in --

6 CHAIR ROBERTS: Okay. Thanks. So, 16 7

will be added, too? Okay, great. Thank you.

8 MR. OBERSON: Thank you, Dan.

9 Let's see. So, circling back, I mentioned 10 the one on the -- go to the next one, Patrick. Yes, 11 I mentioned the one on the Commission policy on 12 microreactor deployment and the fourth one. That's 13 one, I think, for the closed session.

14 So, in conclusion, Westinghouse considered 15 each of the design aspects presented in Reg Guide 16 1.232 and a sufficient set of PDCs for the eVinci 17 design. The core subject is the license limitations 18 and conditions. From the perspective of staff, they 19 established the necessary design testing and 20 performance and provided reasonable assurance that the 21 reactor could be operated without undue risk to the 22 health and safety of the public, and in general, that 23 the TR is suitable for referencing any future license 24 applications.

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44 So again, I do apologize for, like I said, 1

any lack of capacity that I have to address any 2

matters you would have wanted to discuss, but I'm 3

happy to take any questions that I can, and otherwise, 4

pick it up for those matters that are moving to the 5

closed session.

6 Thanks.

7 CHAIR ROBERTS: Yes, adding PDC 16 to that 8

policy No. 2 is a good one. We had a pretty extensive 9

discussion this morning on a different PDC review and 10 it was very similar changes made.

11 MR. OBERSON: Sure.

12 CHAIR ROBERTS: Then, the question was, 13 why the PDC would be written specifically saying use 14 TRISO fuel, which gives you sufficient, you know, 15 containment --

16 MR. OBERSON: Sure.

17 CHAIR ROBERTS: -- versus keeping the 18 functional type of requirement of partial containment 19 that says have multiple barriers and show that. So, 20 maybe you see that as more the generic question for 21 both of these projects --

22 MR. OBERSON: Sure.

23 CHAIR ROBERTS: -- when you're rethinking 24 the desirability of having a more detailed design 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

45 specification as opposed to at the more functional 1

level.

2 MR. OBERSON: Yes. Okay.

3 CHAIR ROBERTS: Okay, great. I guess you 4

know this portion of it?

5 MR. OBERSON: Yes, I got you. Thanks so 6

much. Yes.

7 CHAIR ROBERTS: Okay. Any other questions 8

from members or consultants?

9 MEMBER HALNON: This is Greg. I have one 10 quick one.

11 MEMBER KIRCHNER: Tom?

12 MEMBER HALNON: Go ahead, Walt.

13 MEMBER KIRCHNER: Do you want to go first?

14 MEMBER HALNON: Well, go ahead, Walt. I'm 15 fine.

16 MEMBER KIRCHNER: Tom, yes. Thank you.

17 This is Walt Kirchner.

18 Actually, I wanted to ask the staff about 19 how they were handling -- there's some unique aspects 20 to this design and you addressed one of them earlier.

21 The sodium coolant is really not a primary coolant as 22 we think of it. It's part of a heat pipe system.

23 But the challenge that I see isn't so much 24 that as the fact that the reactor container does not 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

46 completely encapsulate the sodium. So, you have the 1

heat pipes going out from the container to the air 2

Brayton cycle system.

3 So, then, it raises the question of sodium 4

leakage detection and reaction prevention. Because if 5

you have a failure of one of the heat pipes external 6

to the container, now you have the challenge of 7

consequential failure.

8 So, what's your position on -- this would 9

be the SFR sodium fast reactor, Design Criteria No. 73 10 on sodium leakage detection and prevention, and 11 reaction prevention and mitigation. Because it's not 12 just interaction with concrete that's of concern. I 13 would say that's probably of least concerns actually 14 here. It's the air-sodium interaction and the 15 potential additional heat and the loading on the heat 16 pipe itself, and the potential for consequential 17 failure.

18 So, how are you approaching 73 with regard 19 to air-sodium interactions?

20 MR. OBERSON: I guess it's a question, do 21 we believe that it applies to air interactions, 22 sodium-air interactions, or what might, I guess --

23 MEMBER KIRCHNER: Yes. I mean, because it 24 leads to a sodium fire. And traditionally, you know, 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

47 for sodium fast reactors, there's been a guard vessel 1

around the sodium systems to prevent that kind of 2

interaction.

3 MR.

OBERSON:

Yes, I

mean, my 4

understanding of PDC 73 -- and I guess this is a case 5

where I could appeal to even one of the Westinghouse 6

staffers to want to speak to it -- but the intent of 7

PDC 73 as it relates to sodium reaction and reaction 8

prevention mitigation would be addressed by -- the 9

sodium-air interactions would be addressed by that 10 PDC. Does Westinghouse want to speak to that?

11 MR. SMITH: Yes. This is Matt Smith from 12 Westinghouse.

13 I wanted to clarify that there is an 14 additional barrier, and we can get into the details of 15 that during the closed session. But there are two 16 barriers between sodium and air. So, that is a design 17 feature that we are considering here. I wanted to 18 make sure that was clear.

19 MEMBER KIRCHNER: Okay. No. Thank you.

20 I know that. I wanted you to say that for the public.

21 MR. SMITH: Yes, okay.

22 (Laughter.)

23 MR. OBERSON: Noted.

24 MEMBER HALNON: So, this is Greg. I have 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

48 a quick question on some of the language, and you can 1

stay on this slide.

2 You talk about the PDC intent is met.

3 Back in a previous life, we used to use that language 4

to try to show compliance with a regulation because we 5

didn't like the words that were being used and 6

couldn't quite meet the words of the regulation.

7 So, when you say the PDC intent is met, 8

are you, basically, saying this very specific language 9

is equivalent to what the PDC requires or is there 10 something softer there?

11 MR. OBERSON: I mean, I guess I would say 12 that it's soft in the sense that the presumption is 13 the PDC is intended to provide assurance of, you know, 14 provide a level of assurance of safety, I suppose is 15 how I would say it, and that the same assurance is 16 provided by the wording of the specific eVinci PDC, in 17 this case, the eVinci PDC, as would be provided by the 18 sort of generically-written one, but with the change 19 necessary to sort of translate from one design to the 20 other. So, it's sort of a soft --

21 MEMBER HALNON: Okay.

22 MR. OBERSON: Yes, it's sort of a soft 23 intent.

24 MEMBER HALNON: So, we should not read 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

49 into a generic aspect of this, but it's more of a 1

specific eVinci issue?

2 MR. OBERSON: Yes.

3 MEMBER HALNON: And then, are we going to 4

assume that was because of the underlying safety basis 5

words, that there's an equivalent level of assurance 6

of safety?

7 MR. OBERSON: Yes.

8 MEMBER HALNON: Okay. No, I just wanted 9

to get that cleared up. I wanted to make sure I 10 understood what you were meaning there. Because you 11 use it on several of these.

12 Thank you.

13 MR. OBERSON: Yes, I understand. Thank 14 you.

15 CHAIR ROBERTS: Okay. Any other questions 16 or comments from the members and consultants?

17 (No response.)

18 Hearing none, we're going to end the open 19 session.

20 So, anybody from the public who would like 21 to make a comment? Go ahead and unmute yourself; 22 identify your name and affiliation, if appropriate, 23 and then, state your comment.

24 (No response.)

25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

50 Okay. Hearing none, we are now going to 1

close the open session. Okay. So, we're going to 2

close the open session now and, at 2:15 p.m. Eastern, 3

we'll start the closed session.

4 (Whereupon, at 2:01 p.m. EDT, the open 5

session of the Subcommittee was concluded, to resume 6

at 2:15 p.m. EDT in closed session.)

7 8

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1716 14th STREET, N.W., SUITE 200 (202) 234-4433 WASHINGTON, D.C. 20009-4309 www.nealrgross.com

Westinghouse Non-Proprietary Class 3 EVR_LTR_240202 WAAP-13023, Revision 0, eVinci' Microreactor - Principal Design Criteria Topical Report ACRS Subcommittee Meeting - Open Session Westinghouse Electric Company 51 Bridge Street Pittsburgh, PA 15223

1 Westinghouse Non-Proprietary Class 3

eVinci Microreactor 1

August 21, 2024 Principal Design Criteria Topical Report ACRS Subcommittee Meeting - Open Session eVinci is a trademark or registered trademark of Westinghouse Electric Company LLC, its affiliates and/or its subsidiaries in the United States of America and may be registered in other countries throughout the world. All rights reserved. Unauthorized use is strictly prohibited. Other names may be trademarks of their respective owners.

EVR_LTR_240202, Revision 0

2 Agenda

eVinci Microreactor Design Overview

eVinci Microreactor Deployment Model Overview

eVinci Microreactor Nuclear Regulatory Commission (NRC) Pre-Application Engagement to Date

Overview of Principal Design Criteria (PDC) Topical Report (TR)

Questions EVR_LTR_240202, Revision 0

3 eVinci Microreactor Design Safety through passive heat pipe technology, enabling a very low-pressure reactor Parameter eVinci Microreactor Power 15 MWt Fuel Cycle 8 years Fuel (Enrichment)

Tri-structural Isotropic (TRISO) (19.75%)

Coolant Heat Pipes Reactor Pressure

~1 atm Moderator Graphite Power Conversion Open-Air Brayton Efficiency 34%

Decay Heat Removal Radial Conduction Shutdown Rods Steel Canister Radial Reflector Control Drums Graphite Core Block Primary Heat Exchanger Shielding &

Bulkhead Heat Pipes EVR_LTR_240202, Revision 0

4 eVinci Microreactor Site Layout Site and facility shown for single unit All buildings and systems: above ground Reactor site footprint: < 3 acres Building footprint: <0.5 acres EVR_LTR_240202, Revision 0

5 eVinci Microreactor Deployment Model 1

Test reactor for safety feature performance demonstration eVinci microreactor licensing approval Test reactor - testing, data collection and analysis 2

Assemble in factory 3

Transport to site 4

Install and operate at site 5

Primary reactor Replacement reactor Transport away from site 6

Operated reactor Remote monitoring station eVinci Microreactor Deployment Limited site staff with remote monitoring Refuel/refurbish 7

or decommission 8

Fuel storage facility EVR_LTR_240202, Revision 0

6 Current Status:

https://www.nrc.gov/reactors/new-reactors/advanced/licensing-activities/pre-application-activities/evinci.html Topic Submittal Wave Topic Submittal Wave Topic Submittal Wave 1

Facility Level Design Description Submitted - 1 13 Advanced Logic System(ALS) v2 Submitted - 3 25 Inservice Inspection Program/Inservice Testing Program Submitted - 5 2

Principal Design Criteria Submitted - 1 14 Component Qualification Submitted-3 26 Post-Accident Monitoring System Submitted - 5 3

Safety and Accident Analysis Methodologies Submitted - 1 15 Emergency Plan Zone Sizing Methodology Submitted - 3 27 Equipment Qualification Submitted - 5 4

Licensing Modernization Project Implementation Submitted - 1 16 Physical Security Submitted - 3 28 Probabilistic Risk Assessment and Transportation Risk Assessment Submitted - 5 5

Regulatory Analysis Submitted - 2 17 Heat Pipe Design, Qualification, and Testing Submitted - 3 29 Fire Protection Submitted - 5 6

Deployment Model Submitted - 2 18 Nuclear Design Submitted - 3 30 Cyber Security Submitted - 5 7

Safeguards Information Plan Submitted - 2 19 U.S Transportation Strategy Submitted - 3 31 Radiation Protection and Contamination Methodology Submitted - 6 8

Test and Analysis Process Submitted - 2 20 Phenomena Identification and Ranking Table (PIRT)

Submitted - 4 9

Functional Containment and Mechanistic Source Term Submitted - 2 21 Integral Effects and Transient Testing Submitted - 4 10 Composite Material Qualification and Testing Submitted - 2 22 Refueling and Decommissioning Submitted - 4 11 Fuel Qualification and Testing Submitted - 3 23 Seismic Methodology Submitted - 4 12 Code Qualification Submitted - 3 24 Operations and Remote Monitoring Submitted - 4 Pre-Application Engagement - White Papers EVR_LTR_240202, Revision 0

7 Topical Reports Report Title Submittal Date 1

ALS v2 Platform Submitted (Dec. 2022) 2 ALS v2 Development Process Submitted (Dec. 2022) 3 Principal Design Criteria Submitted (Jun. 2023) 4 ALS v2 Technical Specification Surveillance Requirement Elimination Submitted (Dec. 2023) 5 Nuclear Design Methodology Submitted (May 2024) 6 Westinghouse TRISO Fuel Design Methodology Submitted (Aug. 2024) 7 Composite Materials 8

Testing Program 9

Physical Security 10 Functional Containment and Mechanistic Source Term Methodology 11 Design Basis Analysis Methodology 12 Metallic Materials 13 Graphite Materials 14 Heat Pipe Qualification Criteria 15 Component Qualification Methodology 16 Inservice Inspection 17 Inservice Testing EVR_LTR_240202, Revision 0

Principal Design Criteria Topical Report Overview 8

EVR_LTR_240202, Revision 0

9 Section 1.0 - Introduction

NRC white paper feedback (ML22059A460) considered in topical report development

Purpose

eVinci microreactor PDC and the basis for their selection

PDC include safety-related (SR) and non-safety-related with special treatment (NSRST) design criteria (DC)

Derivation of eVinci microreactor PDC based on the following applicable regulations and regulatory guidance:

Guidance for DC provided in Regulatory Guide (RG) 1.232

General Design Criteria (GDC) in Title 10 of the Code of Federal Regulations (CFR) Part 50 Appendix A

Incorporates the safety case for the eVinci microreactor developed based on Nuclear Energy Institute (NEI) 18-04 (endorsed by NRC in RG 1.233) and NEI 21-07 (endorsed by NRC in RG 1.253)

Westinghouse requests NRC review and approval on the set of PDC for the eVinci microreactor, including the list of and justification for the GDC identified as not applicable to the eVinci microreactor.

EVR_LTR_240202, Revision 0

10 Section 2.0 - Summary of the eVinci Microreactor Design and Facility Description See design summary provided in Slides 3-4 EVR_LTR_240202, Revision 0

11 Section 3.0 - PDC Development Summary

PDC derived based on the design criteria in RG 1.232 and GDC in 10 CFR Part 50 Appendix A

Each GDC and DC contained in RG 1.232 reviewed for applicability to design and were either kept as-is, edited, or determined to not be applicable in its entirety

One additional PDC developed not based on GDC or RG 1.232

eVinci microreactor PDC are function-based and not structure, system, or component (SSC) specific; therefore, there is no differentiation between PDC-Required Functional Design Criteria (RFDC) and PDC-Complementary Design Criteria (CDC) as described in NEI 21-07 eVinci microreactor PDC crosswalk provided on Slide 13.

EVR_LTR_240202, Revision 0

12 Section 3.0 - PDC Development Summary

NEI 18-04 (endorsed by RG 1.233) and NEI 21-07 (endorsed by RG 1.253) were used to risk-inform the PDC and confirm PDC for the eVinci microreactor required safety functions (RSFs) were appropriately included

Examples of ways PDC have been revised based on NEI 18-04 and NEI 21-07:

Use of Quality Assurance PDC text from NEI 21-07

Allow for defense-in-depth process to drive need for multiple barriers

Important to safety revised to safety significant

Postulated accidents revised to licensing basis events or design basis accidents (as applicable)

EVR_LTR_240202, Revision 0

13 Section 3.0 - eVinci Microreactor PDC Crosswalk 10 CFR 50 Appendix A GDC Applicable RG 1.232 Appendices eVinci Microreactor PDC Text Compared RG 1.232 PDCs 1

A Modified from RG 2

A Modified from RG 3

A Modified from RG 4

A Modified from RG 5

A Modified from RG N/A (PDC 6 newly defined)

N/A Reactor-specific PDC 10 C

Modified from RG 11 A

Modified from RG 12 A, C Modified from RG 13 A

Modified from RG 14 C

Identical to RG 15 C

Modified from RG 16 C

Modified from RG 17 C

Modified from RG 18 N/A N/A 19 A

Modified from RG 20 C

Modified from RG 21 N/A N/A 22 A

Modified from RG 23 A

Identical to RG 24 A

Identical to RG 25 C

Identical to RG 26 C

Modified from RG 27 N/A N/A 28 A

Modified from RG 29 A

Identical to RG 30 N/A N/A 31 N/A N/A 32 N/A N/A 33 N/A N/A 10 CFR 50 Appendix A GDC Applicable RG 1.232 Appendices eVinci Microreactor PDC Text Compared to RG 1.232 PDCs 34 C

Modified from RG 35 N/A N/A 36 N/A N/A 37 N/A N/A 38 N/A N/A 39 N/A N/A 40 N/A N/A 41 N/A N/A 42 N/A N/A 43 N/A N/A 44 N/A N/A 45 N/A N/A 46 N/A N/A 50 N/A N/A 51 N/A N/A 52 N/A N/A 53 N/A N/A 54 N/A N/A 55 N/A N/A 56 N/A N/A 57 N/A N/A 60 A

Identical to RG 61 A

Modified from RG 62 A

Modified from RG 63 A

Modified from RG 64 A

Modified from RG N/A B (Criterion 71)

Modified from RG N/A B (Criterion 73)

Modified from RG N/A B (Criterion 74)

Modified from RG N/A B (Criterion 78)

Modified from RG Table 3.3-1 in Topical Report EVR_LTR_240202, Revision 0

14 Section 4.0 - eVinci Microreactor PDC

Title:

Provides number and title of PDC. In most cases, the title is from 10 CFR Part 50 Appendix A and/or RG 1.232; however, in some cases the title has been changed to reflect specific aspects of the eVinci microreactor design.

eVinci microreactor PDC: Provides eVinci microreactor PDC wording.

Position: Provides determination of whether a given Advanced Reactor Design Criteria (ARDC), Sodium-Cooled Fast Reactor (SFR)-DC, or Modular High-Temperature Gas-Cooled Reactor (MHTGR)-DC from RG 1.232 (or other source, as applicable) is adopted with or without changes. Modifications made to the underlying design criteria are shown in red with a strikethrough for removed text and in blue with underline for added text. The source DC is provided adjacent to the modifications for convenience.

Basis: Provides justification and rationale for why a certain design criteria (or portion of a certain design criteria) has been determined to be applicable to the eVinci microreactor design. Also describes and justifies changes in text to develop the eVinci microreactor PDC.

Source: Provides the ARDC, SFR-DC, or MHTGR-DC from RG 1.232 (or other source, as applicable).

EVR_LTR_240202, Revision 0

15 Section 4.0 - Example PDC (Modified from ARDC)

Title:

1. Quality standards and records eVinci microreactor PDC:

Safety significant structures, systems, and components shall be designed, fabricated, erected, and tested to quality standards commensurate with the safety significance of the functions to be performed. Where generally recognized codes and standards are used, they shall be identified and evaluated to determine their applicability, adequacy, and sufficiency and shall be supplemented or modified as necessary to assure a quality product in keeping with the safety significant function. A quality assurance program shall be established and implemented in order to provide reasonable assurance that these structures, systems, and components will satisfactorily perform their safety significant functions. Appropriate records of the design, fabrication, erection, and testing of safety significant structures, systems, and components shall be maintained by or under the control of the nuclear power unit licensee for an appropriate period of time.

Position:

PDC 1 for the eVinci microreactor design uses the language in RG 1.232, ARDC 1 with changes to be consistent with the Quality Assurance PDC text in NEI 21-07, Section C, 5.3.1.

RG 1.232, Appendix A, Criterion 1 eVinci microreactor PDC 1 Structures, systems, and components important to safety shall be designed, fabricated, erected, and tested to quality standards commensurate with the importance of the safety functions to be performed. Where generally recognized codes and standards are used, they shall be identified and evaluated to determine their applicability, adequacy, and sufficiency and shall be supplemented or modified as necessary to assure a quality product in keeping with the required safety function. A quality assurance program shall be established and implemented in order to provide adequate assurance that these structures, systems, and components will satisfactorily perform their safety functions. Appropriate records of the design, fabrication, erection, and testing of structures, systems, and components important to safety shall be maintained by or under the control of the nuclear power unit licensee throughout the life of the unit.

Safety significant structures, systems, and components important to safety shall be designed, fabricated, erected, and tested to quality standards commensurate with the importance safety significance of the safety functions to be performed. Where generally recognized codes and standards are used, they shall be identified and evaluated to determine their applicability, adequacy, and sufficiency and shall be supplemented or modified as necessary to assure a quality product in keeping with the required safety significant function. A quality assurance program shall be established and implemented in order to provide adequate reasonable assurance that these structures, systems, and components will satisfactorily perform their safety significant functions. Appropriate records of the design, fabrication, erection, and testing of safety significant structures, systems, and components important to safety shall be maintained by or under the control of the nuclear power unit licensee throughout the life for an appropriate period of the unit time.

Basis:

This requirement is applicable, because the eVinci microreactor contains safety significant SSCs that are designed, fabricated, erected, and tested to quality standards that correspond with the importance of the safety functions that need to be performed. The eVinci microreactor will follow the Westinghouse Quality Management System.

The phrase important to safety is changed to safety significant to align with the terminology in the proposed Quality Assurance PDC in NEI 21-07, Section C, 5.3.1.

The phrase throughout the life of the unit was changed to for an appropriate period of time to account for the application of quality assurance special treatments to NSRST SSCs. Again, this aligns the PDC text with NEI 21-07, Section C, 5.3.1.

Source:

RG 1.232, Appendix A, Criterion 1 and NEI 21-07, Section 5.3.1 EVR_LTR_240202, Revision 0

16 Section 4.0 - Example PDC (Newly Developed)

Title:

6. Monitoring, inspection, and testing eVinci microreactor PDC:

Safety significant structures, systems, and components shall be designed to permit monitoring, surveillance, periodic inspection, and/or testing as necessary to ensure functional capability commensurate with the safety significance of the functions to be performed. Functional testing shall ensure the operability and performance of the system components, and the operability of the system as a whole and, under conditions as close to design as practical, the performance of the full operational sequence that brings the system into operation, including associated systems, for licensing basis events.

Position:

PDC 6 of the eVinci microreactor design uses the language from RG 1.232, MHTGR-DCs 18, 21, 32, 36, 37, 39, 40, 45, and 46 into a single PDC for monitoring, inspection, and testing.

RG 1.232, Appendix C eVinci microreactor PDC 6 No generic monitoring, inspection, and testing PDC in RG 1.232.

Safety significant structures, systems, and components shall be designed to permit monitoring, surveillance, periodic inspection, and/or testing as necessary to ensure functional capability commensurate with the safety significance of the functions to be performed. Functional testing shall ensure the operability and performance of the system components, and the operability of the system as a whole and, under conditions as close to design as practical, the performance of the full operational sequence that brings the system into operation, including associated systems, for licensing basis events.

Basis:

Generic wording is used to support a single monitoring, testing, and inspection PDC, which replaces the need for RG 1.232, MHTGR-DCs 18, 21, 32, 36, 37, 39, 40, 45, and 46.

Monitoring, surveillance, periodic inspection, and/or testing will be established as special treatments in accordance with the NEI 18-04 integrated decision-making process (IDP) and will meet the performance intent of the eVinci microreactor. Accordingly, the eVinci microreactor inservice inspection and inservice testing programs will be developed to support inspection and testing needs that are identified through the NEI 18-04 process.

Additionally, the Inspections, Tests, Analyses, And Acceptance Criteria (ITAAC), to be defined in the DCA will inform what is required in terms of testing and inspection prior to operation.

The phrase safety significant is used in this PDC to align with the risk-informed, performance-based (RIPB) terminology used in NEI 18-04 and NEI 21-07.

Source:

RG 1.232, Appendix C, Criteria 18, 21, 32, 36, 37, 39, 40, 45, and 46 EVR_LTR_240202, Revision 0

17 Section 4.0 - Example PDC (Identical to RG 1.232)

Title:

14. Reactor helium pressure boundary eVinci microreactor PDC:

The reactor helium pressure boundary shall be designed, fabricated, erected, and tested so as to have an extremely low probability of abnormal leakage, of rapidly propagating failure, of gross rupture, and of unacceptable ingress of moisture, air, secondary coolant, or other fluids.

Position:

PDC 14 for the eVinci microreactor design uses the language in RG 1.232, MHTGR-DC 14 with no changes.

RG 1.232, Appendix C, Criterion 14 eVinci microreactor PDC 14 The reactor helium pressure boundary shall be designed, fabricated, erected, and tested so as to have an extremely low probability of abnormal leakage, of rapidly propagating failure, of gross rupture, and of unacceptable ingress of moisture, air, secondary coolant, or other fluids.

The reactor helium pressure boundary shall be designed, fabricated, erected, and tested so as to have an extremely low probability of abnormal leakage, of rapidly propagating failure, of gross rupture, and of unacceptable ingress of moisture, air, secondary coolant, or other fluids.

Basis:

This requirement is applicable because the eVinci microreactor has a helium environment in the reactor canister. This PDC addresses the need to consider leakage of contaminants into the helium in the reactor canister.

Source:

RG 1.232, Appendix C, Criterion 14 EVR_LTR_240202, Revision 0

18 Section 4.0 - Example N/A GDC

Title:

27. Combined reactivity control systems capability GDC:

The reactivity control systems shall be designed to have a combined capability, in conjunction with poison addition by the emergency core cooling system, of reliably controlling reactivity changes to assure that under postulated accident conditions and with appropriate margin for stuck rods the capability to cool the core is maintained.

Screening Rationale for GDC Being N/A:

The objective of this requirement is satisfied by PDC 26 for reactivity control.

EVR_LTR_240202, Revision 0

Questions 19 EVR_LTR_240202, Revision 0

20 EVR_LTR_240202, Revision 0

NRC Staff Review of the Westinghouse Principal Design Criteria Topical Report for the eVinci Microreactor Design Patrick Boyle, Project Manager Michelle Vega Rodriguez, Associate Project Manager Dan Beacon, Nuclear Engineer Office of Nuclear Reactor Regulation Division of Advanced Reactors and Non-Power Production and Utilization Facilities

Agenda

Review chronology

Topical report (TR) purpose and review strategy

Safety evaluation (SE) overview

Conclusions 2

Review Chronology

June 28, 2023: WEC eVinci PDC topical report (TR), Rev. 0 submitted.

Aug. 15, 2023: TR accepted for review.

Sept. 15 and Oct. 31, 2023: Clarification meetings held.

Nov. 16, 2023: Requests for Additional Information (RAIs) issued.

Dec. 15, 2023: RAI responses submitted by WEC.

May 15, 2024: WEC eVinci PDC TR, Rev. 1 submitted.

Edits to reflect the items discussed during the clarification meeting discussions and RAIs.

July 26, 2024: NRC Staffs Draft Safety Evaluation Issued (ML24176A132) 3

TR Purpose and Review Strategy

Purpose of TR:

Provide PDCs to support both the design and licensing process and compliance with pertinent regulatory requirements of Title 10 of the Code of Federal Regulations (10 CFR) Parts 50 and 52 associated with PDCs.

Review strategy

Review conformance with Regulatory Guide (RG) 1.232

Evaluate deviations from RG 1.232 in consideration of the key eVinci design features

Consider applicability of RG 1.232 appendices and guidance to novel eVinci design features 4

Safety Evaluation Overview

Regulations and guidance

eVinci design features (informational)

eVinci PDCs

PDCs effectively identical to RG 1.232 Design Criteria (DCs)

PDCs influenced by NEI 18-04 terminology and approach

PDCs related to fuel storage

PDCs with specific considerations

RG 1.232 DCs and GDCs found not applicable

Limitations and conditions

Conclusions 5

Regulations

In accordance with the provisions of 10 CFR Parts 50 and 52, applicants for a construction permit (CP), operating license (OL), standard design certification (DC), combined license (COL), standard design approval (SDA), or manufacturing license (ML) must submit PDCs for the proposed facility. Specifically,

10 CFR 50.34(a)(3)(i), which requires, in part, that applications for a CP include PDCs for the facility.

An OL would reference a CP, which would include PDCs.

10 CFR 52.47(a)(3)(i), which requires, in part, that applications for a standard DC include PDCs for the facility.

10 CFR 52.79(a)(4)(i), which requires, in part, that applications for a COL include PDCs for the facility.

10 CFR 52.137(a)(3)(i), which requires, in part, that applications for an SDA include PDCs for the facility.

10 CFR 52.157(a), which requires, in part, that applications for a ML include PDCs for the reactor to be manufactured.

10 CFR Part 50, Appendix A provides requirements on the scope and content of PDCs for non-light water reactors (non-LWRs):

The principal design criteria establish the necessary design, fabrication, construction, testing, and performance requirements for structures, systems, and components important to safety; that is, structures, systems, and components that provide reasonable assurance that the facility can be operated without undue risk to the health and safety of the public.

6

Guidance

RG 1.232, Guidance for Developing Principal Design Criteria for Non-Light Water Reactors (ML17325A611)

Appendices provide example DCs

RG 1.233, Guidance for a Technology-Inclusive, Risk-Informed, and Performance-Based Methodology to Inform the Licensing Basis and Content of Applications for Licenses, Certifications, and Approvals for Non-Light Water Reactors (ML20091L698)

Endorses NEI 18-04, Risk-Informed Performance-Based Technology Inclusive Guidance for Non-Light Water Reactor Licensing Basis Development, Revision 1 (ML19241A472)

RG 1.253, Guidance for a Technology-Inclusive Content of Application Methodology to Inform the Licensing Basis and Content of Applications for Licenses, Certifications, and Approvals for Non-Light-Water Reactors, (ML23269A222) was in draft form (DG-1404) at the time of submittal.

Endorses NEI 21-07, Technology Inclusive Guidance for Non-Light Water Reactors - Safety Analysis Report: For Applications Utilizing the NEI 18-04 Methodology, Revision 1 (ML22060A190).

7

eVinci Design Features

High-temperature heat pipe reactor, 15MWth

Tri-structural isotropic (TRISO) fuel, compacts, high-assay low-enriched uranium (HALEU)

Horizontal hexagonal graphite blocks, thermal neutron spectrum

Normal heat removal: Heat pipes to open-air Brayton cycle

Decay heat removal: Conduction and radiation to environment (passive)

Reactivity control: Drums, shutdown rods, and inherent feedback

Functional containment (TRISO layers, Reactor Canister)

No active electrical power to perform required safety functions

Transportable 8

eVinci PDC Overview

Most PDCs are based on ARDC-DCs (Appendix A of RG 1.232)

Some PDCs are based on SFR-DCs (Appendix B of RG 1.232)

Sodium is contained in the heat pipes as the working fluid

Some PDCs are based on MHTGR-DCs (Appendix C of RG 1.232)

Design similarities: fuel, core, vessel, functional containment and materials

New PDC 6 proposed

Combines multiple monitoring, inspection, and testing related DCs 9

PDCs effectively identical to RG 1.232 DCs

Applicable PDCs: 10, 11, 14, 15, 23, 24, 25, 28, 29, and 60

The above eVinci PDCs were found acceptable on the bases that:

The proposed language is effectively identical to the RG 1.232 DCs.

Differences in language or terminology, if any, did not change intent of PDC.

Ex: PDC 11, Changing systems to structures, systems and components.

Design assumptions for the RG 1.232 DCs are applicable to the eVinci design.

The underlying safety basis of RG 1.232 remains applicable for each, as applied to the eVinci design.

10

PDCs influenced by LMP terminology

Applicable PDCs: 1, 2, 3, 4, 5, 16, 20, and 22

The above eVinci PDCs use similar language as RG 1.232 DCs, with key terminology changes to reflect planned LMP implementation.

RG 1.233: Applicants referencing this RG are expected to use the terminology in NEI 18-04

Replace important to safety and postulated accident from RG 1.232 DC with safety-significant and licensing basis event to align with language from NEI 18-04 (and NEI 21-07).

Underlying safety basis remains applicable to the eVinci design.

11

PDCs influenced by the LMP approach

Applicable PDCs: 6, 17, 26, 34, and 78

RG 1.253 was in draft (DG-1404), so refinement of the PDCs into RFDCs + CDCs was not implemented in this topical report.

The NEI 18-04 approach includes an evaluation of defense-in-depth adequacy intended to address concerns related to independence, redundancy, diversity, and defense-in-depth.

RG 1.232 DC language regarding these concepts was therefore removed.

Only acceptable if used with LMP licensing approach

Limitation/Condition 2 12

PDCs related to storage

eVinci PDCs 61, 62, and 63 modify RG 1.232 DC language to reflect reactor fuel handling and storage plans for the eVinci design.

Replace concepts of fuel storage, waste, and associated handling with the concept of reactor storage to reflect the fueled-reactor unit deployment and handling approach being sought for implementation.

Technical and regulatory aspects of fueled-reactor handling and storage were under Commission consideration at the time of review.

(SECY 24-0008)

Condition/Limitation 3: Only acceptable if, in a future licensing submittal, fueled-reactor storage is found to conform with Commission policy 13

PDC 12 - Suppression of Power Oscillations

eVinci PDC 12 combined portions of RG 1.232 Appendix A and C.

Reflects broader applicability of SSCs than ARDC-12.

Reactor core, associated structures, and associated coolant, control, and protection systems

Reflects the use of SARRDLs, consistent with MHTGR-DC 12, rather than SAFDLs.

Similarity in fuel design and radionuclide retention approach

Found appropriately applicable to the eVinci design and that RG 1.232 safety basis is maintained.

14

PDC 17 - Electric power systems

Incorporates LMP terminology changes: safety significant, required safety function, and design basis accidents.

[Discussion deferred to closed session]

Electrical power for RSFs (if needed) is covered by the PDC, regardless.

15

PDC 19 - Microreactor control

Adapts ARDC 19 language [Discussion deferred to closed session]

Removed text about shutdown capabilities that is redundant to other PDC requirements (i.e. PDC 26).

PDC accepted with Limitation/Condition 4:

[Discussion deferred to closed session]

16

PDC 64 - Monitoring Radioactive Releases

Changes to RG language reflect functional containment approach and LMP terminology.

TR Rev. 0 included additional specificity with undefined terminology.

Public meeting held for discussion between NRC and Westinghouse

PDC 64 Revised in TR Rev. 1 to more closely align with RG 1.232 ARDC 64.

PDC intent and underlying safety basis aligns with RG 1.232 and eVinci design.

17

PDC 71 - Cover gas purity control

eVinci PDC 71 is adapted from RG 1.232, Appendix B, SFR-DC 71.

Applicability to helium cover gas purity in the eVinci reactor canister.

Removed SFR-DC 71 language that referred to sodium primary coolant.

eVinci PDC 73 pertains to detection of sodium leakage and/or reactions from hermetically sealed heat pipes.

PDC intent of maintaining primary cover gas purity and underlying safety basis aligns with RG 1.232 and remains applicable in the context of the eVinci design.

18

PDC 73 - Sodium leakage detection and reaction prevention and mitigation

eVinci PDC 73 is adapted from RG 1.232, Appendix B, SFR-DC 73.

The SFR-DC 73 language is expanded with a requirement to ensure passive heat removal system availability.

Language regarding sodium-concrete interactions is removed.

Multiple non-concrete barriers exist between the sodium contained in heat pipes and any concrete structures outside the reactor canister or primary heat exchanger.

PDC intent and underlying safety basis aligns with RG 1.232 and remains applicable in the context of the eVinci design.

19

PDC 74 - Sodium/water reaction prevention/mitigation

eVinci PDC 74 adopts the applicable portion of RG 1.232, Appendix B, SFR-DC 74.

Language regarding steam-water energy conversion systems is removed because eVinci relies on an open-air Brayton conversion system.

PDC intent and underlying safety basis aligns with RG 1.232 and remains applicable in the context of the eVinci design.

20

PDC 78 - Sodium heat pipe interfaces

eVinci PDC 78 is adapted from RG 1.232, Appendix B, SFR-DC 78.

Changes reflect that sodium is only contained in heat pipes, and not as a primary coolant.

Language associated with redundancy is removed to reflect the use of LMP and the associated DiD adequacy assessment.

PDC intent and underlying safety basis aligns with RG 1.232 and remains applicable in the context of the eVinci design.

21

Safety Evaluation Overview

Regulations and guidance

eVinci design features (informational)

eVinci PDCs

PDCs effectively identical to RG 1.232 Design Criteria (DCs)

PDCs influenced by NEI 18-04 terminology and approach

PDCs related to storage

PDCs with specific considerations

RG 1.232 DCs and GDCs found not applicable

Limitations and conditions

Conclusions 22

PDCs related to monitoring, inspection and testing

RG 1.232 DCs 18, 21, 32, 36, 37, 39, 40, 45, and 46 pertain to monitoring, inspecting, and testing of various specific SSCs.

Similar language used in each.

eVinci PDC 6 encompasses these criteria into a single PDC.

Effectively mirrors the language of the replaced criteria.

Applicability encompasses all replaced criteria.

PDC intent and underlying safety basis aligns with that of the replaced RG 1.232 criteria.

23

Heat transport functions, Reactor coolant system boundary - DCs 30, 31, and 33

DCs 30, 31, and 33 are not directly applicable to the unique heat removal design of the eVinci reactor (heat pipes).

The DCs refer to a reactor coolant system, but the eVinci design does not include any forced convection or primary coolant as meant in RG 1.232.

Review approach: Ensure the fundamental safety concepts intended by DCs 30, 31, and 33 are addressed by PDCs.

Concepts: Reactor coolant system (reactor canister/HPB, in the eVinci context) integrity, retainment of radioactive materials, appropriate heat removal, and monitoring/prevention of air, moisture, or other fluid ingress.

24

Heat removal and emergency cooling - DCs 35, 38, and 44

DCs 35, 38, and 44 objectives focus on adequate heat removal capability to cool the core, containment, and associated SSCs.

25

Functional Containment - DCs 41, 42, 43, and 50-57

DCs 41, 41, 43, and 50-57

[Discussion deferred to closed session]

26

Limitations and Conditions (L&Cs) 1.

Westinghouse is requesting approval for the proposed PDCs based on a preliminary design and plans to incorporate the NEI 18-04 and NEI 21-07 processes (subsequently referred to as the licensing modernization project (LMP) in its licensing approach). The eVinciTM design changes and associated LMP implementation could necessitate a revision to the proposed PDCs described in the TR. Therefore, future licensing applicants referencing the TR must confirm that the PDCs in this TR remain appropriate for its design. If additional or revised PDCs are identified that are not within the scope of what is approved in this TR, those PDCs will be subject to further NRC staff review.

2.

The eVinciTM PDCs 6, 17, 26, 34, and 78 include language that reflects the implementation of the LMP. Specifically, departures from NRC endorsed PDC development guidance are made, including the removal or replacement of language regarding defense-in-depth, redundancy, independence, and/or diversity. The NRC staff finds the proposed language of these PDCs acceptable based on the assumption that the LMP process will be implemented during licensing and will address the topics of defense-in-depth, redundancy, independence, and/or diversity. As such, the NRC staff finds eVinciTM PDCs 6, 17, 26, 34, and 78 acceptable only when referenced to support the licensing of a design or facility that also includes the implementation of the LMP in its licensing approach.

27

Limitations and Conditions (L&Cs) 3.

The NRC staff acknowledge that PDCs 61, 62 and 63 are developed to support eventual implementation of a fueled microreactor unit deployment strategy. The NRC staff finds the PDCs acceptable on the condition that such an approach will be deemed acceptable in a future licensing action. The NRC staff makes no determination in this SE regarding the acceptability of transporting, manipulating, and/or storing a fueled microreactor unit. Such a determination would be subject to future licensing actions and subject to the requirements deemed applicable to those actions.

4.

[Discussion deferred to closed session]

28

Conclusions

Westinghouse considered each of the design aspects presented in RG 1.232.

Westinghouse provided a sufficient set of PDCs for the eVinci design, subject to the L&Cs.

The PDCs (subject to the L&Cs) establish the necessary design, fabrication, construction, testing, and performance DC for safety significant SSCs to provide reasonable assurance that the eVinci reactor could be operated without undue risk to the health and safety of the public.

The TR is suitable for referencing in future licensing applications for the eVinci reactor.

29

Abbreviations ARDC - Advanced reactor design criteria CDC - Complimentary design criteria CFR - Code of Federal Regulations CP - Construction permit DANU - Division of Advanced Reactors and Non-Power Production and Utilization Facilities DBA - Design basis accident DC - Design criterion DG - Draft Guide DiD - Defense in depth GDC - General design criterion HALEU - High-assay low-enriched uranium L&C - Limitation and/or condition LMP - Licensing Modernization Project LWR - Light water reactor MHTGR - Modular high temperature gas reactor NEI - Nuclear Energy Institute NRC - Nuclear Regulatory Commission NRR - Office of Nuclear Reactor Regulation PDC - Principal design criterion RAI - Request for additional information RFDC - Required functional design criteria RG - Regulatory guide RSF - Required safety function SAFDL - Specified acceptable fuel design limit SARRDL - Specified acceptable system radionuclide release design limit SFR - Sodium fast reactor SSC - Structure, system, or component SE - Safety evaluation TR - Topical report TRISO - Tri-structural Isotropic WEC - Westinghouse Electric Company 30

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